Filed of the Invention
The techniques of the present specification relates to a method for producing a Group III nitride semiconductor single crystal through a flux method.
Background Art
Semiconductor crystals are produced through vapor-phase growth methods such as metal-organic chemical vapor deposition (MOCVD) and hydride vapor phase epitaxy (HVPE); molecular beam epitaxy (MBE); and liquid-phase epitaxy. One liquid-phase epitaxy technique is a flux method employing Na flux.
In a general procedure of the flux process, a gallium nitride (GaN) layer is formed on a sapphire substrate or a like substrate, to thereby form a seed-crystal substrate, and a semiconductor single crystal is grown on the seed-crystal substrate in a melt. The seed-crystal substrate, raw materials of the semiconductor single crystal, and a flux are placed in a crucible, and then the semiconductor single crystal is grown while the temperature and pressure in the reaction chamber are controlled. There is disclosed a technique for transferring nitrogen gas from the vapor-liquid interface into the melt through stirring the melt (refer to, for example, paragraph [0003], Table 1, etc. of Japanese Patent Application Laid-Open (kokai) No. 2010-168236).
When semiconductor single crystals are grown through a flux method, semiconductor single crystals are sometimes not grown depending on the growth conditions. Even when semiconductor single crystals could be grown, it is difficult to obtain uniform semiconductor single crystals over the entire surface of the seed crystal substrate. Reproducibility of semiconductor single crystals is sometimes unstable. That is, it is by no means easy to stably grow semiconductor single crystals.